TapWaterGuide
Worldwide water safety reference
United States Last reviewed:

Idaho Tap Water Quality

about 790
Community water systems
1
City reports on this site
3
Tracked contaminants
August 28, 2026
Data reviewed

Check a Idaho ZIP Code

Overview

Idaho drinks almost entirely from groundwater, including the vast Snake River Plain aquifer, one of the most productive in the world. Boise's system (run by Veolia) blends aquifer wells with treated Boise River water and meets all federal standards.

Water quality is generally very good. The persistent issues are nitrate from irrigated agriculture and dairies in the Magic Valley and eastern Snake Plain, naturally occurring arsenic and uranium in some southern wells, and the usual small-system capacity gaps in a largely rural state.

Common Contaminants in Idaho

Nitrate

Idaho's most tracked contaminant; agricultural regions show rising trends and some small systems and private wells exceed the limit

Arsenic

Naturally occurring in southwest and south-central Idaho groundwater; a recurring small-system violation

Uranium

Detected above limits in a handful of southern Idaho wells; treated or blended where found

Violations & Compliance

Boise and the larger cities are consistently compliant. Violations concentrate in small agricultural-area systems for nitrate and arsenic, and the state maintains nitrate priority areas where groundwater degradation is documented.

City Water Reports in Idaho

Frequently Asked Questions

Sources & References

The safety rating and guidance on this page draw on the following sources. See our full methodology.